.Net程序员玩转Android开发---(17)Handler用法

来源：互联网发布：两心之外无人知歌词编辑：程序博客网时间：2024/06/05 17:52

在android开发中，如果在一个线程中想更新主界面中控件显示的数据，直接给主界面控件赋值就会出现异常，android中为了安全起见，是不允许在线程中更新界面控件的数据，遇到这种情况，我们可以使用Handler. Handler就是处理界面和线程间的消息传递，通信的组件。下面我们演示下handler处理详细的两种办法,下面的这个列子通过点击不同按钮展现handler.post和handler.sendmsg两个传递消息的方法。

1. Handler.Post

创建一个handler对象和Runnable对象，通过handler.post(new Runnable(){});处理来更新界面中的textview的数据

2.Handler.sendMessage

这个例子中，我们创建一个employee员工类，单击按钮的时候，显示员工的信息，通过handler.sendmessage来传递消息和参数进行处理

全部代码

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical" >    <TextView        android:id="@+id/textViewMsg"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="TextView" />    <Button        android:id="@+id/btnpost"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="handler post" />    <Button        android:id="@+id/btnmsg"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="handler message" />    </LinearLayout>

package com.example.helloword;import android.R.string;import android.app.Activity;import android.os.Bundle;import android.os.Handler;import android.os.Message;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.SimpleAdapter;import android.widget.TextView;public class HandlerActivity extends Activity {private TextView tv;private Button btnpost;private Button btnmsg;private Handler handler=new Handler();//post处理handler//sendmsg处理handlerprivate Handler handlerTwo=new Handler(){public void handleMessage(Message msg) {switch (msg.what) {case 0:tv.setText("姓名:"+((employee)msg.obj).name);break;}}};protected void onCreate(Bundle savedInstanceState) {// TODO Auto-generated method stubsuper.onCreate(savedInstanceState);setContentView(R.layout.handlerlayout);tv=(TextView)findViewById(R.id.textViewMsg);btnpost=(Button)findViewById(R.id.btnpost);btnmsg=(Button)findViewById(R.id.btnmsg);btnpost.setOnClickListener(new OnClickListener(){@Overridepublic void onClick(View arg0) {// TODO Auto-generated method stubThread thread=new Thread(new Runnable(){@Overridepublic void run() {// TODO Auto-generated method stubhandler.post(runOne);}});thread.start();}});btnmsg.setOnClickListener(new OnClickListener(){@Overridepublic void onClick(View arg0) {// TODO Auto-generated method stubThread thread=new Thread(new Runnable(){@Overridepublic void run() {// TODO Auto-generated method stubMessage msg=new Message();msg.arg1=1;employee employeeone=new employee();employeeone.name="员工1";employeeone.age=20;msg.obj=employeeone;msg.what=0;handlerTwo.sendMessage(msg);}});thread.start();}});}    Runnable  runOne=new Runnable(){@Overridepublic void run() {// TODO Auto-generated method stubtv.setText("正在执行handler post");}    };            public class employee    {      public String name;      public int age;    }}

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